The present invention relates to staples intended to fix items to a delicate material of low density and low strength, such as a friable material of the type formed from a layer of plaster between two cardboard sheets.
The items to be fixed may include metal wires and elements made from synthetic material, such as electrician""s channelling.
Already known is a fixing staple for delicate material, formed from an assembly of two flexible legs extending between a head portion connecting the legs and an introduction end portion, the assembly providing, between the two portions, head and end, a discontinuity portion so that when it is pushed into the material, at least one of the legs inclines with respect to the head portion and thus ensures good resistance to extraction.
Such a staple is disclosed, among others, in GB 2238591 and DE 3623712.
With the staple of these references, the leg which can be inclined is longer than the other in order to converge more easily towards the other when being pushed in, the discontinuity portion of the assembly extending around the shorter leg.
Still, when the staple is pushed in, even if the leg which can be inclined is the only one to really become inclined and if the shorter leg only inclines slightly with respect to the head, the inclination of the large leg should suffice to hold the staple. By reason of the difference in length of the two legs of the staple, creating the discontinuity portion, it should be possible to avoid, during insertion, the legs remaining parallel to each other or their inclination with respect to the head portion remaining invariable when being pushed in in the direction of the force applied to the staple. Furthermore, when the shorter leg is pushed in it should increase the convergence of the two legs.
However, with such a type of staple, inclination of the legs is still not always perfect or efficient.
The instant invention aims to propose a staple which is better suited to soft and friable materials.
To this end, the invention relates to a fixing staple for soft material of the type herein above defined, characterized in that the two legs are bent inwards in the discontinuity portion of the assembly in order to diverge from one another when being pushed in.
Thanks to the bent portion of the legs of the staple, the length of the legs has been increased, and hence their flexibility, and therefore the assurance of their divergence has also been increased as well as of an outstanding resistance to extraction, without increasing the overall length of the staple.
In a preferred manner, the legs are chamfered from the inside to the outside as far as their introduction end.
It is also advantageous that the widths of the head portion and introduction end portion are substantially equal.
The staple can be formed from a strand which has a cross-section selected from a circle, rectangle and oval.